These bookmarklets let you see how a web page is coded without digging through the source, debug problems in web pages quickly, and experiment with CSS or JS without editing the actual page.
The original Suckerfish Dropdowns article published in A List Apart proved to be a popular way of implementing lightweight, accessible CSS-based dropdown menus that accommodated Internet Explorer by mimicking the :hover pseudo-class. Well now they're back and they're more accessible, even lighter in weight (just 12 lines of JavaScript), have greater compatibility (they now work in Opera and Safari without a hack in sight) and can have multiple-levels.
a test tool for web applications. Selenium tests run directly in a browser, just as real users do. And they run in Internet Explorer, Mozilla and Firefox on Windows, Linux, and Macintosh. No other test tool covers such a wide array of platform.